Geckos in general are reptilian and are normally born with a pair of fins behind their heads. Their eyes possess an orange tint, and their body coloration differs greatly based on the gecko sub-species in question. Geckos have evolved with five fingers and five toes. Dependent on type, they range from the size of a small human child, to heights exceeding that of average human adults.

Geckos are generally found in small packs. Once a single gecko attacks something or is attacked, its pack will join the fight. They charge or leap at their opponents with their mouths open, ready to snap down, along with being known to simply attack rapidly with their claws. Some sub-species of geckos can breathe fire or spit a poisonous liquid, so that they may also attack from a distance.

Their hides and meat prove useful as survival crafting ingredients; in particular the hides, once tanned, can be used to craft several varied types of armor that offer greater defense than their base variants along with resistances to fire, poison, and radiation.

Geckos, green geckos, and golden geckos are affected by the Animal Friend perk. Fire geckos, however, remain hostile to the Courier with the perk. This is because fire geckos are classified as abominations, while other geckos are classified as animals. This means that fire geckos will flee if shot with a flare gun, just like any other abomination will do (which is remarkable considering their accustomedness to fire).

Geckos appear in small to large packs depending the location. They will charge at their prey with their mouths open, and attack by biting and with swipes from their claws. Geckos can be found mostly in the areas surrounding Goodsprings, along the I-15 towards Primm and the Mojave Outpost. These are the least dangerous species of gecko found within the Mojave.

These geckos may appear alongside golden geckos and attack in the same way. Their bites are similarly irradiated, dealing less radiation/second but for a longer period of time. Golden gecko hunter melee attacks do similar damage to regular golden gecko melee attacks.

Golden geckos that have yet to mature. They are seldom found alone and are usually found with adult geckos. Although weaker than matured variants, their speed makes them a threat to inexperienced players.

Fire geckos have mottled purple and red hides, and prominent spikes on their backs. In addition to their bite and claw attacks, they have the ability to breathe fire. They can mainly be found in and around mountainous areas and caves, such as the Lucky Jim Mine and Nopah Cave.

The legendary fire gecko is one of the five legendary creatures. It is roughly twice the size of a normal fire gecko and its powerful and fast attacks makes it a dangerous opponent in close combat. It is found in Fire Root cavern.

Green geckos are native to and only found in Zion Canyon. When attacking from a distance, they can spit several far-reaching but slow-moving globs of poisonous saliva, somewhat resembling the radioactive spit attack that centaurs use. Once in contact with an enemy, they will attack like other types of gecko, by biting and clawing. Green geckos are almost always found in packs ranging from two to eight. Green geckos are often found near waterways and bridges in Zion Canyon.

Several friendly geckos appear in the main Sorrows camp in Honest Hearts. They are possibly tamed.

Geckos deal heavy damage to limbs, especially the head.

Another type of fire gecko exists, but was cut from the final product. Its name is Gojira. Simply called "gecko" when spawned, Gojira is its editor ID. It's identical to the fire gecko, but about triple the size and has a whopping 8,000 HP.

pcps3xbox360 Geckos may not always be hostile to the Courier, even if the player doesn't possess the Animal Friend perk. However, getting too close or trying to speak to one may turn it hostile. [verified]

xbox360 Green geckos inhabiting Zion Canyon may not be hostile to the Courier, and approaching or attempting to talk to them will not change their disposition. If you happen to shoot one of these geckos, simply put away one's weapon and it will return to being friendly, just like a normal non-player character. [verified]

xbox360 In the Mojave Desert, several young gecko hunters may be found superimposed upon one another, but not moving from the spot except to flail their arms and roar loudly. They cannot be damaged with guns, and when attacked and killed with a melee weapon, the game freezes and must be reset. [verified]